4 GEOLOGY OF OHIO. 



elephant, mastodon, and giant beaver are found in and above the Forest 

 Bed, but nowhere yet below it. 



6th. Above the old soil which has been described we find a series of 

 stratified deposits, sometimes of considerable thickness, evidently the 

 product of a submergence by which a large land area was deeply buried 

 beneath a mass of transported material. In southern Ohio these later 

 Drift deposits consist of white, laminated brick-clay, yellow and blue 

 clays, the latter containing bowlders, and sometimes heavy beds of gravel 

 and sand. In the northern counties of Ohio the upper strata of the Drift, 

 and the equivalents of those last mentioned, are laminated, usually some- 

 what sandy clays, and locally beds of sand and gravel, which, from the 

 fact that they have been washed down from the watershed, and have 

 been transported by the draining streams, have been sometimes referred 

 to as the Delta sand deposit. In western Ohio, Indiana, Illinois, etc., the 

 uppermost stratum of the Drift is called the Loess or Bluff formation. All 

 the deposits enumerated in this note are the products of the last sub- 

 mergence, and I have termed them the Lacustrine Drift. They will be 

 described in detail in another place. 



7th. Upon the clays, sands, gravels, etc., last mentioned are scattered 

 bowlders and blocks of all sizes of granite, greenstone, silicious and 

 mica slates, etc., etc., generally traceable to some locality in the Eozoic 

 area north of the lakes. Among these have been found many masses of 

 native copper, which were plainly derived from the copper district of 

 Lake Superior. These bowlders are found on nearly all the drift-covered 

 area of the State ; being scattered over the summit of the watershed, 

 and reaching south nearly or quite to the Ohio. The margin of the 

 bowlder area seems to mark the outline of the great ice-sheet at the 

 period of its greatest development, but most of the bowlders strewed over 

 this area appear to have been deposited by another agency, at a much 

 later date. The greater part of them lie on or near the surface, and in 

 many instances they rest on beds of purely laminated clay, and hence 

 could never have reached their present positions through the agency 

 of glaciers or powerful currents of water. They must, therefore, have 

 been floated to their present resting places. The evidence is conclusive 

 that they were transported by icebergs, and hence I have called them 

 the Iceberg Drift. 



8th. The highlands of Ohio, as well as in Michigan, New York, Wis- 

 consin, etc., are locally occupied by hills, ridges, and banks of well 

 rounded gravel and sand, with some bowlders which correspond closely 

 with the " Karnes " and " Eskers " of the Old- World Drift. These peculiar 

 accumulations of drifted material were evidently produced by special and 



